1,256 publications from this institution
Abstract This paper examines theoretical results on finite‐time synchronization and fixed‐time synchronization analysis for delayed reaction–diffusion with nonidentical parameters. Using finite‐time stability and fixed‐time stability theorems, Lyapunov functional, feedback control laws, and techniques involving inequalities, serval novel assertions are made to achieve the finite/fixed‐time synchronization of the proposed system. These results are new and complement existing works in the field. Finally, two simulation examples are provided to validate the proposed approaches.
This paper investigates the stability analysis of cubature Kalman filter (CKF) for nonlinear systems with linear measurement. The certain conditions to ensure that the estimation error of CKF remains bounded are proved. Then, the effect of process noise covariance is investigated and an adaptive process noise covariance is proposed to deal with large estimation error. Accordingly, a modified CKF (MCKF) is developed to enhance the stability and accuracy of state estimation. The performance of the MCKF is compared to the CKF by two case studies. Simulation results demonstrate that the large estimation error may lead to instability of CKF while the MCKF is successfully able to estimate the states.
In this paper, an adaptive neural output-feedback tracking controller is designed for a class of multiple-input and multiple-output nonstrict-feedback nonlinear systems with time delay. The system coefficient and uncertain functions of our considered systems are both unknown. By employing neural networks to approximate the unknown function entries, and constructing a new input-driven filter, a backstepping design method of tracking controller is developed for the systems under consideration. The proposed controller can guarantee that all the signals in the closed-loop systems are ultimately bounded, and the time-varying target signal can be tracked within a small error as well. The main contributions of this paper lie in that the systems under consideration are more general, and an effective design procedure of output-feedback controller is developed for the considered systems, which is more applicable in practice. Simulation results demonstrate the efficiency of the proposed algorithm.
In this paper, the joint actuator fault estimation (AFE) and the wheeled mobile robot (WMR) localization under the Round-Robin protocol (RRP) problems are concerned. In order to complete the joint AFE and the WMR localization, a nominal joint system is constructed, which consists of the drive subsystem and WMR localization subsystem. In the drive subsystem of the WMR, the DC motor is used as an actuator to drive the WMR. When the faults occur, the performance of the actuator will be degraded, and the mobility of the WMR will be affected. In order to maintain a satisfactory mobility of the WMR, the faults need to be estimated timely such that some appropriate decisions or remedies can be made. In the WMR localization subsystem, for saving the network resources, the RRP is introduced to schedule the transmission of sensor measurements used for the WMR localization. The purpose of this paper is, by designing a time-varying filter for the constructed joint nominal system, to ensure the filtering error to meet the given [Formula: see text] performance requirement, such that the joint AFE and the WMR localization can be achieved simultaneously. Specifically, the sufficient condition is derived first and then the desired filter gain is designed by the recursive linear matrix inequality technology. Finally, a simulation experiment is conducted to certify the usefulness of the proposed algorithm.
No abstract is provided for this article.
In multi-autonomous underwater vehicle (multi-AUV) systems, the convergence rate is characterized by the pace of consistency of the key state information for each member. The topology with leader-follower architecture is designed as a combination of an undirected graph between followers and a digraph between leaders and followers. An overview of influences on convergence rate of the second-order consensus algorithm is elaborated in three aspects, along with the main contributions in this paper. Specifically, the explicit expression of the maximum convergence rate is established based on the root locus method, and then, the effects of control parameters on the convergence rate are analyzed. Moreover, the influences of network topologies on the convergence rate are investigated from the view of adjusting the existing connectivity, changing the weights on links, and utilizing hierarchical structure. The combination of consensus and filtering algorithm is also an approach to enhance the capacity of multi-AUV systems. In order to eliminate the accumulated errors in the process of dead reckoning, a collaborative navigation model is presented, and then, a localization approach based on consensus-unscented particle filter algorithm is proposed. Simulations results are provided to verify location performance under the assumption of Gaussian white noise in the systems. In addition, the influences of the topologies on positioning accuracy are explored.
No abstract is provided for this article.
This paper presents the work in the area of sensing, using smart materials, more specific dielectric electro active polymers (DEAPs). Sensing is one of the main trio-characteristics of DEAPs; the trio-formations as applicable uses are actuator, transducer, and finally sensor. It is noted that one of the main value propositions whenever DEAP material is used, is the dual characteristics as the sensing/actuating capability. In the following work, the DEAP membrane will be modeled and the relation among the key variables (pressure and capacitance) will be determined. Hence, such a relation depends on the geometrical shape of the used membrane. The development process is carried out to propose alternative solutions for the sensor design using the DEAP and the laminate material. Test methodology, pressure-based test rig, prototypes, and software are developed afterwards to evaluate the prototypes test pieces. In general, the DEAP material has proven to be a very good sensor for pressure taking the advantage of flexibility, wide range of operation, and finally the sensitivity. The theoretical model is benchmarked against the acquired data from the tests, whereby high correlation within an approximate range of 0-23 mmHg (1.7% mean error) has been observed showing a promising application for the DEAP material in pressure sensing in general, and demonstrating the feasibility for the conceptualization of the blood pressure sensing system based on DEAP material.
A Mahalanobis hyperellipsoidal learning machine class incremental learning algorithm is proposed. To each class sample, the hyperellipsoidal that encloses as many as possible and pushes the outlier samples away is trained in the feature space. In the process of incremental learning, only one subclassifier is trained with the new class samples. The old models of the classifier are not influenced and can be reused. In the process of classification, considering the information of sample’s distribution in the feature space, the Mahalanobis distances from the sample mapping to the center of each hyperellipsoidal are used to decide the classified sample class. The experimental results show that the proposed method has higher classification precision and classification speed.
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In this paper, the synchronization issue for network systems with nonlinear dynamics is considered. Together with zero-order holder, the aperiodic sampled-data control law is utilized. Compared with the traditional periodic sampled-data control method, this approach demonstrates more greater flexibility. Adopting input delay approach, the initial sampled-data system is remodeled by continuous time system involving time-varying delays in the control signals. For the purpose of designing the sampling controllers suffering constant delays, an updated Lyapunov functional is developed from the augmentation of Wirtinger's inequality. Such a Lyapunov functional results in efficient and simplified synchronization conditions. A sufficient condition for synchronizability of network systems is set up. Then, for the case of unstable systems with some constant delays, a fresh discretized Lyapunov functional is introduced. Finally, we utilize the numerical simulation outcomes to prove the efficacy and advantage of our algorithm. Moreover, based on the network unmanned ground vehicle systems, the experiment results in a real scenario are provided to illustrate the effectiveness of the designed synchronization scheme.
This paper is concerned with the measurement outlier-resistant mobile robot localization problem by using multiple Doppler-azimuth radars under round-robin protocol (R-RP). In the considered robot localization system, multiple Doppler-azimuth radars are equipped on the robot platform to produce the measurement including the Doppler frequency shift and the azimuth. In order to assuage communication link congestion, the R-RP is used. For mitigating the influence of outliers, a time-varying state estimator is constructed which contains a saturation function with variable saturation levels. This paper aims at seeking out a practicable yet effective solution to the addressed robot localization problem by devising the constructed estimator which can assure that, over a finite horizon, the localization error satisfies the given H ∞ performance index. By constructing an appropriate Lyapunov function, the sufficient condition, which can guarantee the localization error to fulfill the given H ∞ performance, is established. Then, by resorting to the solution to a set of linear matrix inequalities, the constructed estimator can be devised. In the light of the estimator design strategy proposed in this paper, the corresponding robot localization algorithm is developed. At last, some simulations are conducted to testify the usefulness of the developed robot localization algorithm.
Multi-standard software definable radios (SDR) which are capable of operation according to a variety of different mobile radio standards represent an extremely powerful tool for evolution towards future third-generation cellular systems. An approach based on the use of a fixed-bandwidth analogue front-end for the implementation of a wideband digital SDR receiver was introduced by Karimi and Friedrichs (see, IEE Colloquium on Adaptable and Multi-Standard Mobile Radio Terminals, 1997) and the resulting impact on analogue-to-digital converter technology investigated. This paper examines a number of the architectural issues and trade-offs involved in the design and implementation of the digital signal processing aspects of such wideband receivers in the context of multi-standard GSM/DCS/UMTS digital radios. This work has been undertaken in the context of the FIRST project (Flexible Integrated Radio System Technology) as part of the ACTS mobile domain.
